tubing size for a-arms?
 

ok I need to order tubing for my a-arms by the end of the week. I am getting some 4130 chrome moly tubing from wicksaircraft.com (local place) but I need to select a tubing size still. the arms are about 16" long with an air bag mounted on them. would some 1.25"x .090" tubing be too overkill? this is on a daily driver so pothole durability ranks higher then weight savings right now....but I won't want to TOTALLY overbuild the setup. I was even thinking of something as large as 1.375"x.090" tubing.

You're likely to not get an answer to your question because you're asking someone to engineer a load bearing weldment that will be subjected to some nasty vibration and shock loads, as well as having a probable finite cycle life. If someone did suggest a tube size, they have no control over (no offense meant here) the quality of the welds nor the overall design.

If it failed, no matter the failure mode, the person that gave you advice could, in reality, be held partially at fault for the failure and any resulting property damage or even loss of life. As a matter of fact, I would urge anyone to avoid answering this question, or questions like it unless they have the proper insurance coverage for the situation.

Sorry dude...blame the lawyers.

ok maybe then as a better question....

what tubing sizes are used on commerically available arms?

PS...sorry $1 stag beer night nextdoor

Jim Meyer Racing has built the last 2 chassis' for me. On his design he used 1" upper & 1.25 lower. But he used mild steel DOM rather than chromoly. I have been told not to use chromoly on the street for building chasiss for a few reasons, but not sure on control arms. This is a little out of my league as to the true reasons not to. That's why I leave it to the people that know when it comes down to stuff like this! :D

could anyone else chimein on this? I could se the CM not being used since it is stiffer and would be a rougher ride than the mild. Part of the thing is that I am graduating with my under grad in mechanical engineering but none of the professors around here know anything about this kind of a situation. I have the knowledge to do the FEA on it but just don't know what kind of loading I am loking at IE is a 10,000 lb force along the cars axis enough to simulate a pothole pushing the wheel back? what about vertical forces?

Air Ride tech control arms are 1in DOM

well what wall thickness? I was looking at going to a larger diameter tube with a thinner wall maybe.....but the wall thickness is the most important part

just looked in the book .219 wall thickness

so what is the problem with 4130 tubing? just by changing to that I could cut the wall thickness in half.

I don't know that there is a problem with chrome moly...maybe companies don't use it because it is more expensive! :_paranoid